The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Powertrain systems of vehicles may employ engine autostopping strategies to shutdown an engine when a vehicle is stopped. For instance, when a vehicle is stopped at a traffic light and an operator of the vehicle has a brake pedal depressed, the engine can be automatically stopped and shut down (e.g., fuel cut-off event). When vehicle motion is desired, the engine can automatically start to provide motive torque to the drive wheels. One drawback of automatically stopping and starting an engine is that electrical energy required from an energy storage device to supply a starter motor for cranking the engine can temporarily result in large voltage drops at auxiliary loads of the vehicle to which the electrical energy storage device is also supplying energy to. These voltage drops, commonly referred to as voltage sag, can result in diagnostic faults in the electrical system, controller resets and other undesirable electrical anomalies such as vehicle interior lighting flicker and accessories being interrupted.
It is known to utilize a DC-DC boost converter to boost sagging battery voltages during an autostart to supply stable voltage to certain critical loads. However, DC-DC boost converters require partitioning of all the electrical loads that are supported and are limited to low power loads, e.g., loads less than about 400 Watts. Another drawback of DC-DC converters is that higher load power leads to accelerated deterioration of battery voltage during the auto start and ineffective voltage stabilization. Additionally, DC-DC boost converter use on vehicles with higher electrical loads is cost prohibitive.